The American National Standard for Telecommunications is developing a standard that sets forth spectrum management requirements and recommendations for the administration of services and technologies that use metallic subscriber loop wire pairs, commonly referred to as subscriber loops. The goal of the standard is to administer the loop plant in a way that provides spectral compatibility for services and technologies that use pairs in the same cable binder. The standard is particularly directed to minimizing the potential for cross-talk interference in twisted pair subscriber loop cables that are shared by multiple service providers (carriers). In situations where multiple service providers utilize twisted pairs in the same loop binders, services and technologies may interfere with each other if they are deployed in an uncontrolled manner. The standard provides spectrum management requirements and deployment recommendations for the administration of services and technologies in such an environment in a way that prevents or minimizes such deleterious effects.
The Spectrum Management Classes address (1) transmit signal power spectral density (PSD) requirements, (2) transmit signal average power requirements, (3) transverse balance requirements, (4) deployment restrictions based upon the subscriber loop characteristics, and (5) loop assignment guidelines. A communication device or system that meets all of the applicable requirements for one of the spectrum management classes is deemed to be in conformance with the standard. If a communication device or system does not meet all of the requirements associated with at least one of the spectrum management classes, the communication device or system is deemed to be non-compliant with the standard.
It would be desirable to provide a communication device, such as a digital subscriber line (DSL) modem, for example, that is capable of operating in a manner that is compatible with one or more of the spectrum management classes. It would also be desirable to provide a communication device that is capable of automatically detecting which of the spectrum management classes it is capable of operating in and of automatically selecting a mode of operation that is compatible with one of the spectrum management classes. Furthermore, it would be desirable to provide such a communication device that could detect when it is capable of operating in a mode that is compatible with more than one of these classes and that would automatically select a mode of operation that is compatible with the class that optimizes performance of the communication device. It would also be desirable to provide such a communication device that could detect when it is no longer capable of operating in a mode that is compatible with at least one of the spectrum management classes and which would prevent operation of the communication device when such a determination is made.
Although it is generally known for certain DSL modems and subscriber line technologies to have automatic and adaptive algorithms that seek to optimize performance, it is not known to provide a modem that detects compatibility with one or more spectrum management classes of the aforementioned standard and that selects the appropriate or best mode of operation based on that determination. For example, algorithms that automatically select transmit spectrum bandwidths and/or bandwidth locations are known. These algorithms are utilized to optimize performance in accordance with the ITU V.34 standard. The ITU V.34 standard also provides for adaptive equalizers and echo-cancelers.
Another type of automatic algorithm provided for by the ITU V.34 standard, which is often referred to as an auto-rating algorithm, provides for modifying a data transmission rate of a modem to allow the highest data rate possible to be utilized in the presence of certain line impairments. However, this algorithm is not truly “adaptive” because it is necessary to temporarily disrupt communication while the rate change is being accomplished. An auto-rate algorithm that is utilized with Multiple Virtual Lines (MVL) technology is known, which was developed by the assignee of the present application. The MVL auto-rating algorithm enables the rate change to be accomplished without disrupting communication. Therefore, the MVL auto-rating algorithm is adaptive.
Although the aforementioned algorithms seek to optimize performance, they do not take into account restrictions on transmit bandwidth and/or transmit power level or other types of restrictions that are in effect on a particular subscriber line on which they operate. These are examples of the types of restrictions that must be met in order to comply with the spectrum management classes defined in the standard. Therefore, these algorithms are not suitable for automatically selecting an appropriate mode of operation that is in compliance with one of the spectrum management classes.
A feature known as Spectrum Manager is used with Etherloop modems, which are marketed by a company known as Elastic Networks. Etherloop modems base the use of transmit spectrum on the presence or absence of other devices in the binder, i.e., on the presence or absence of other devices communicating on the same copper pair. Etherloop modems correlate an allowable use of spectrum to the length of the loop to which the modem is connected. The Etherloop modem adjusts its usage of transmit spectrum based on a detection of cross-talk caused by other DSL systems in the binder.
However, the Etherloop modem does not adjust its use of spectrum based on loop parameters required for spectrum management class compliance. Furthermore, when an Etherloop modem is operating properly, it will, under many circumstances, select modes of operation that are not in compliance with the aforementioned spectrum management classes. Also, Etherloop modem adjustments are based on a measurement of transient conditions and other conditions that are difficult to measure. It is not based on measurement parameters that are directly related to the deployment rules associated with the spectrum management classes.
Accordingly, a need exists for a communication device, such as a modem, that is capable of detecting whether it is capable of operating in a mode that is compatible with one or more of the spectrum management classes and which automatically selects a mode of operation that is compliant with one of the spectrum management classes. A need also exists for such a communication device that is capable of determining whether it is capable of operating in multiple modes that are compliant with multiple spectrum management classes and which is capable of selecting the mode of operation that optimizes the performance of the communication device. A need also exists for such a communication device that is capable of determining when it is not capable of operating in a mode that is compliant with at least one of the spectrum management classes and which prevents operation of itself upon determining that it is not capable of operating in a mode that is compliant with at least one of the spectrum management classes.